Shrink tunnel with turntable

ABSTRACT

A portable shrink tunnel with turntable means for heat shrinking plastic film about various objects to be wrapped. The shrink tunnel is provided with a turntable disc having a loading station in which the objects are wrapped and placed on the turntable, a heat-shrinking station within an overlying shrink tunnel that may be expandable to cover one-quarter to one-half of the turntable, and a discharge station on the turntable which is adjacent the receiving station. The turntable is constantly rotated and carries the objects to be wrapped 360* from the receiving station, through the shrink tunnel, and the discharge station. The shrink tunnel is composed of two arcuate housing sections telescopically adjustable to vary the tunnel length, and provide a means for controlling the tunnel heat supplied in the tunnel and also to vary the area of the loading or receiving station. A heating element may be positioned underneath the turntable disc at the receiving station to heat the disc which aids in maintaining the wrapping film about the article to be wrapped before it is charged to the heat shrink tunnel.

United States Patent [72] Inventor Richard F. Schramm St. Louis, Mo.

[21] Appl. No. 695,408

[22] Filed Jan. 3, 1968 [45] Patented May 18, 1971 [73] Assignee SpeedEquipment Incorporated St. Louis, Mo.

[54] SHRINK TUNNEL WITH TURNTABLE 6 Claims, 10 Drawing Figs.

[52] US. Cl 34/184,

53/184, 126/338, 263/7 [51] Int. Cl F26b 11/00 [50] Field of Search34/184,

3,256,420 6/1966 Werrnan ABSTRACT: A portable shrink tunnel withturntable means for heat shrinking plastic film about various objects tobe wrapped. The shrink tunnel is provided with a turntable disc having aloading station in which the objects are wrapped and placed on theturntable, a heat-shrinking station within an overlying shrink tunnelthat may be expandable to cover onequarter to one-half of the turntable,and a discharge station on the turntable which is adjacent the receivingstation. The turntable is constantly rotated and carries the objects tobe wrapped 360 from the receiving station, through the shrink tunnel,and the discharge station. The shrink tunnel is composed of two arcuatehousing sections telescopically adjustable to vary the tunnel length,and provide a means for controlling the tunnel heat supplied in thetunnel and also to vary the area of the loading or receiving station. Aheating element may be positioned underneath the turntable disc at thereceiving station to heat the disc which aids in maintaining thewrapping film about the article to be wrapped before it is charged tothe heat shrink tunnel.

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SUMMARY OF THE INVENTION This invention relates to improvements inportable apparatus for heat shrinking film about objects as disclosed inBurke US. Pat. No. 3,164,939. Such apparatus, commonly tenned shrinktunnels, employ a continuously moving belt to receive articles to bewrapped at a receiving station and transport them through a housingemployed as a shrink tunnel to an end portion overlying the continuouslymoving belt at a discharge station to discharge the plastic film wrappedobjects. Heat platen means have been employed under a heatconductivebelt in such apparatus to provide means for heating a belt and lightlytack or shrink the overlapping ends of the film as it is wrapped aboutthe objects at the receiving station to loosely hold the objectstogether before they are charged to the shrinking tunnel.

The instant invention provides improvements in the aforementioned shrinktunnel apparatus by providing a turntable in the form of aheat-conductive platelike disc element, which rotates through areceiving station, a shrinking station, and a discharge station. Theturntable, by its very nature, does not flex as in a continuously movingbelt and thereby avoids any breakdown of the belt due to a continuousflexing and obviates problems in dislodging or tracking of the belt. Inaddition, through this invention, the shrink tunnel housing overlyingthe turntable can be telescopically adjusted in order to vary the lengthof travel and, of course, time of travel within the tunnel area. Thisobviates any necessity to vary the speed of the turntable or to vary thetemperature within the turntable, both of which could be effected ofcourse by electrical control means. By the adjustment of the telescopicshrink tunnel housing, the total heat provided and length of travel canbe varied, coupled with increases or decrease in the area of thereceiving station portion of the turntable. The turntable is furtherprovided with a self-guiding gate separating the discharge station fromthe receiving station, such that when articles that are wrapped aredischarged from the outlet of the tunnel to the discharge area they areguided off the turntable so as not to interfere with the receivingstation.

The shrink tunnel provided with the turntable of this invention can besimply employed by relatively unskilled operators in institutions suchas hospitals, and the like, schools, restaurants, grocery stores, andwherever objects are to be wrapped with heat-shrinkable plastic film. Anextensive measure of control is provided for various types of objects ordifferent types of heat-shrinkable film requiring different amounts ofheat through the means for varying the total time through the shrinktunnel. The versatility of the shrink tunnel makes it adaptable forvarious form of usage, The apparatus is rugged and yet simple to operateand maintain.

The above features are objects of this invention and further objectswill appear in the detailed description which follows and will beotherwise apparent to those skilled in the art.

For the purpose of illustration of this invention, there is shown in theaccompanying drawings a preferred embodiment thereof. It is to beunderstood that these drawings are for the purpose of illustration onlyand that the invention is not limited thereto.

In the drawings:

FIG. 1 is a top plan view of the heat shrink oven with the turntable ofthis invention; I

FIG. 2 is a view in front elevation of the oven;

FIG. 3 is a view in side elevation of the oven taken from the right sideof FIG. 1;

FIG. 7 is a fragmentary top plan view showing the mounting of theturntable and the location of the heat platen, the view being taken asindicated by the line 7-7 of FIG. 2;

FIG. 8 is a bottom plan view of the adjustable left portion of the heatoven housing;

FIG. 9 is a bottom plan view of the stationary right-hand portion of theheat oven housing; and

FIG. 10 is a fragmentary top plan view similar to FIG. 1 but showing theheat oven partially telescoped to reduce the time of dwell within it.

DESCRIPTION OF THE INVENTION Referring now to the drawings, the portableshrink tunnel apparatus of this invention is generally identified by thereference numeral 20 in FIGS. 1 through 4. It is comprised of aframelike base 22, a turntable 24 having a receiving station 26, atelescopic shrink tunnel 28, and a discharge station 30.

The framelike base 22 is best shown in FIGS. 1, 4, 5, 6 and 7. As thereshown, it is comprised of a frame having hollow front and rear members31and 32 and side members 34 and 36. A pair of longitudinally extendingside base supports 38 and 40 extend from the front to the rear of theframe and support it, as shown in FIGS. 1, 4 and 5. A central brace 42likewise extends from the front to the rear of the frame and is boltedon the front and rear members as shown in FIGS. 4 and 7.

The turntable 24 is comprised of a motor 44 mounted upon the brace 42and having a shaft 46 which is fixed to a hub plate 48. The hub plate isconnected to a perforated metal turntable plate 50. The turntable plate50 is provided with a peripheral sleeve 51, which is in registry withroller bearings 52 to provide a wearing surface and reinforcement at theperipheral edges of the turntable plate. This turntable plate overliesthe central portions of the left, rear, and side members of the frameandis supported in load-bearing relation on the roller bearings, whichare mounted in the hollow frame members as best shown in FIGS. 4 and 6.A heating element in the form of a heat platen 56 is mounted under thereceiving station 26 and is attached to the side frame member 34, asbest shown in FIGS. 1, 4 and 7.

The shrink tunnel 28, as best shown in FIGS. 1, 2 and 8- 10, iscomprised of a stationary arcuate housing 58 which is mounted upon ahousing and a movable arcuate housing 60 which is in telescopic relationwith the stationary housing. These housings are shown in 90 arcuatecross section, but it will be understood that they may be either moreorless as desired. The stationary housing 58 is provided with a mountingplate 61, which is fixed to the side of the housing and is mounted uponthe side frame member 36, as shown in FIGS. 1 and 3. The housing 58 isfurther provided with an opening 62 which receives a portable hot airblower 64 which may be inserted therein for heating purposes, or removedfor manual heat shrinking outside the shrink tunnel as desired. Theshrink tunnel housing section 58 is further provided with a dog-earedextension 66, which underlies a corresponding dog-cared section 68 onthe housing section 60, which, with a pivot pin or shaft 70, providesfor pivotal telescopic relative movement betweenthe two sections, as'will appear in FIG. 10. The arcuate housing 60 is additionally providedwith a handle 72 to provide for manual movement of the housing from theextended position shown in FIG. 1 to the retracted position shown inFIG. 10. i

The housing 60 is provided with a flexible split curtain 74 as shown inFIG. 2. This curtain defines an inlet into the shrink tunnel. Thestationary arcuate housing 58 is likewise provided shrink tunnel to thedischarge station 30.

A baffle or guide means 78 is provided as shown in FIGS. 1 and 4 todefine the line of demarcation between the receiving station 26 andthedischarge station 30. The baffle 78 is comprised of a pair oflongitudinally extending support elements 80 and 82, which receiveroller bearings 84 as best shown in with a split flexible curtain 76,which defines an outlet for the FIG. 4. An angled extension 86 providesfor mounting to the front frame member 31. The roller bearings in thebaffle 78 automatically guide the wrapped articles as they aredischarged from the shrink tunnel to the discharge station 30 to directthe articles off the discharge station to the front of the shrink tunnelapparatus as viewed in FIG. 1.

OPERATION The shrink tunnel of this invention is simply set up for useby merely starting the motor 44, which provides for rotation of thetumtahle plate 50. The hot air blower 64 is then energized to provideheat in the shrink tunnel 28 and the two communicating arcuate sections58 and 60. Lastly, the heat platen 56 is energized to provide heat boththrough convection of air passing through the perforated holes in theturntable plate and through radiation by heating the plate itself. Theapparatus is now ready for use.

The operator wraps the desired object to be wrapped with heat-shrinkableplastic film and then places the object with the overlying wrapped endsdownward directly upon the slowly rotating turntable plate at thereceiving station 26. The contact of the overlapped ends of the filmwith the heated turntable plate will cause partial shrinking or.tackingof the overlapped edges, such that the wrapped film does not easilybecome dislodged and can be simply carried on the turntable through theinlet opening 74 into the shrink tunnel. The wrapped object is thencarried through the shrink tunnel and for the period of time that itpasses therein is subjected to heat to cause the shrinking of the filmtightly about the object to be wrapped. The object is then carriedthrough the split curtain discharge or outlet opening 76 onto thedischarge station 30 where it is moved by rotation of the plate againstthe baffle 78. The compound movement prow'ded by the articles upon therotating plate in contact with the roller bearings 84 and the bafilewill cause the article to be discharged to the front of the apparatus ata point adjacent the right side of the baffle viewed in FIG. 1.

The shrink tunnel is shown in the fully expanded position of the movablearcuate section 60 and the stationary housing section 58. Where it isdesired to reduce the period of dwell in the shrink tunnel, a partialtelescopic movement is effected by moving the arcuate section bygrasping the handle 72 and simply moving it to the position shown inFIG. 10. This not only reduces the dwell but also provides a greaterworking surface over the receiving station 26 where this is desired. Itwill be apparent that other measures of control of the heat provided inthe period of time that the wrapped article is subjected to the heat canbe effected by varying the speed of the turntable motor and by varyingthe hot air temperature of the hot air blower 64. However, the simplestmeans is effected through this invention by simply contracting orexpanding the telescopic housing as aforedescribed.

Various changes and modifications may be made within the invention aswill be readily apparent to those skilled in the art. Such changes andmodifications are within the scope and teaching of this invention asdefined by the claims appended hereto.

lclaim:

l. A shrink tunnel for use in heat-shrinking plastic-wrapping film aboutobjects to be wrapped comprising a base, a turntable heat-transferableobject-supporting disc, means for rotating said disc, a station abovesaid disc for receiving articles to be wrapped, a heat-shrinking stationabove said disc adjacent said receiving station defined by a housingextending above said disc, means for heating said housing, aheat-retaining inlet connecting said receiving station with said housingand a heatretaining outlet in said housing opening into a dischargestation situated above said disc, said inlet and outlet having means forpassing the wrapped objects carried by the disc while preventing anysubstantial loss of heat within said tunnel, said housing having meansfor adjusting the length of travel between said inlet and outlet bymeans for varying the arcuate length of the heat-shrinking station.

2. The shrink tunnel of claim 1 in which the means for adjusting thelength of travel between said inlet and outlet comprises a pair ofcontiguous arcuate telescopic housing shell members.

3. The shrink tunnel of claim 2 in which said shell members arecomprised of a stationary housing and a relatively movable housingpivoted for telescopic movement at the axis of said turntable disc.

4. The shrink tunnel of claim 3 in which each of said shell members isprovided with a heat-retaining split curtain covering an opening in theshell member extending above the turntable disc defining an inlet andoutlet to the hat shrink station housing.

5. A shrink tunnel for use in heat-shrinking plastic-wrapping film aboutobjects to be wrapped comprising a base, a turntable heat transferableobject-supporting disc, means for rotating said disc, a station abovesaid disc for receiving articles to be wrapped, a heat-shrinking stationabove said disc adjacent said receiving station defined by a housingextending above said disc, means for heating said housing, aheat-retaining inlet connecting said receiving station with said housingand a heatretaining outlet in said housing opening into a dischargestation situated above said disc, said inlet and outlet having means forpassing the wrapped objects carried by the disc while preventing anysubstantial loss of heat within said tunnel, said tunnel comprising asquare rimlike frame defining an opening in the center, a base extendingacross the bottom-of said frame, a motor mounted upon said basecomprising said disc-rotating means and bearing means at the sides ofthe frame in load-bearing relation to the periphery of the turntabledisc.

6. A shrink tunnel for use in heat-shrinking plastic-wrapping film aboutobjects to be wrapped comprising a base, a tumtable heat transferableobject-supporting disc, means for rotating said disc, a station abovesaid disc for receiving articles to be wrapped, a heat-shrinking stationabove said disc adjacent said receiving station defined by a housingextending above said disc, means for heating said housing, aheat-retaining inlet connecting said receiving station with said housingand a heatretaining outlet in said housing opening into a dischargestation situated above said disc, said inlet and outlet having means forpassing the wrapped objects carried by the disc while preventing anysubstantial loss of heat within said tunnel, a vertically extendingbaffle overlying said disc separating the receiving station from saiddischarge station, said bafile being positioned to direct the wrappedobjects off the turnta ble, said baffle being comprised of radiallyextending member supporting roller bearing elements adapted to becontracted by the wrapped objects in the discharge station.

1. A shrink tunnel for use in heat-shrinking plastic-wrapping film aboutobjects to be wrapped comprising a base, a turntable heat-transferableobject-supporting disc, means for rotating said disc, a station abovesaid disc for receiving articles to be wrapped, a heat-shrinking stationabove said disc adjacent said receiving station defined by a housingextending above said disc, means for heating said housing, aheat-retaining inlet connecting said receiving station with said housingand a heat-retaining outlet in said housing opening into a dischargestation situated above said disc, said inlet and outlet having means forpassing the wrapped objects carried by the disc while preventing anysubstantial loss of heat within said tunnel, said housing having meansfor adjusting the length of travel between said inlet and outlet bymeans for varying the arcuate length of the heatshrinking station. 2.The shrink tunnel of claim 1 in which the means for adjusting the lengthof travel between said inlet and outlet comprises a pair of contiguousarcuate telescopic housing shell members.
 3. The shrink tunnel of claim2 in which said shell members are comprised of a stationary housing anda relatively movable housing pivoted for telescopic movement at the axisof said turntable disc.
 4. The shrink tunnel of claim 3 in which each ofsaid shell members is provided with a heat-retaining split curtaincovering an opening in the shell member extending above the turntabledisc defining an inlet and outlet to the heat shrink station housing. 5.A shrink tunnel for use in heat-shrinking plastic-wrapping film aboutobjects to be wrapped comprising a base, a turntable heat transferableobject-supporting disc, means for rotating said disc, a station abovesaid disc for receiving articles to be wrapped, a heat-shrinking stationabove said disc adjacent said receiving station defined by a housingextending above said disc, means for heating said housing, aheat-retaining inlet connecting said receiving station with said housingand a heat-retaining outlet in said housing opening into a dischargestation situated above said disc, said inlet and outlet having means forpassing the wrapped objects carried by the disc while preventing anysubstantial loss of heat within said tunnel, said tunnel comprising asquare rimlike frame defining an opening in the center, a base extendingacross the bottom of said frame, a motor mounted upon said basecomprising said disc-rotating means and bearing means at the sides ofthe frame in load-bearing relation to the periphery of the turntabledisc.
 6. A shrink tunnel for use in heat-shrinking plastic-wrapping filmabout objects to be wrapped comprising a base, a turntable heattransferable object-supporting disc, means for rotating said disc, astation above said disc for receiving articles to be wrApped, aheat-shrinking station above said disc adjacent said receiving stationdefined by a housing extending above said disc, means for heating saidhousing, a heat-retaining inlet connecting said receiving station withsaid housing and a heat-retaining outlet in said housing opening into adischarge station situated above said disc, said inlet and outlet havingmeans for passing the wrapped objects carried by the disc whilepreventing any substantial loss of heat within said tunnel, a verticallyextending baffle overlying said disc separating the receiving stationfrom said discharge station, said baffle being positioned to direct thewrapped objects off the turntable, said baffle being comprised ofradially extending member supporting roller bearing elements adapted tobe contracted by the wrapped objects in the discharge station.